The true fluence spectra and its conversion coefficients from the air kerma to the ICRU operational quantities for our low-energy X-ray radiation field were determined using spectrometry. The pulse height spectra were measured with a PIPS detector for the ISO reference radiations (N-15 to N-30 and L-20 to L-30). According to the calculated detector response matrices, the measured pulse height spectra were unfolded. Then the average photon energy and the first half-value layer for each radiation quality were calculated and compared with the recommended or measured values. The conversion coefficients from the air kerma to the ICRU operational quantities Hp(10), H*(10), Hp(0.07) and H′ (0.07) and the revised operational quantities ambient dose H*, personal dose Hp and personal absorbed dose in local skin Dp local skin were determined. This work presents the spectrometry and dosimetry for the filtered low-energy X-ray radiations based on a PIPS detector spectrum measurement system in detail. This portable spectrum measurement system can help calibration laborites simplify the experimental setup when performing the dosemeter calibrations according to ISO 4037–4.